This invention relates to a disk cartridge made into a cassette so as to be mounted on a drive device with a disk-like recording medium contained therein.
In recent years, optical disks have been utilized as information recording mediums in the field of the custoday of information and data. An optical disk has a recording surface on the front surface thereof and has both surfaces covered with protective coatings. An optical signal such as a laser light is used to read information from the recording surface of the disk, and therefore when a flaw or flaws, e.g., dust, stains, etc. are present on the surfaces of the protective coatings, reading of information becomes impossible. So it is known to contain the disk within a case, but it is inconvenient to put the disk into and out of the case each time the disk is used, and directly touching the disk with the hand leads to the possibility of imparting a flaw or flaws such as dust, stains, etc. to the disk. In order to prevent this, disk cartridges with a shutter mechanism which can be used without being put into and out of a case are used nowadays.
However, since the optical disk is rotated while being contained in a disk cartridge, the dimensions of the inner wall of the disk containing portion must be made sufficiently greater than the outer diameter of the disk with the amount of eccentricity between the disk and rotating portion of a recording-reproducing apparatus taken into account. Also, during transportation or the like of the cartridge, the disk may slidingly contact with the inner surface of the cartridge, whereby the disk may be injured or scraped, rendering reading of the information on the disk impossible.
As a method for solving such problem, there is a method of designing a stepped portion on the inner surface of the disk containing portion at such a position that will bear against only the inner peripheral portion and/or the end portion of the disk which is a non-recording portion. The stepped portion causes the disk to float up from the inner surface of the cartridge and hold the disk. However, where a stepped portion is provided on the inner peripheral surface of the disk containing portion at such a position that will bear against only the inner peripheral portion of the disk, an extraneous shock applied to an upper case can distort the upper case and the recording portion on the outer peripheral portion of the disk will contact with the inner surface of the cartridge and damage the disk. Where a stepped portion is provided on the inner surface of the disk containing portion at such a position that will bear against only the end portion of the disk, an extraneous shock applied to the upper case will distort the upper case and the recording portion on the inner peripheral portion of the disk will contact the inner surface of the cartridge and damage the disk.
It is the object of the present invention to eliminate the above-noted disadvantages and to provide a disk cartridge which can contain a disk therein without the inner surface of the cartridge contacting the recording portion of the disk and which is simplified in internal structure and can be manufactured at a low cost.
The gist of the present invention for achieving the above object is a disk cartridge for containing a disk-like recording medium therein, characterized in that a stepped portion is provided on the inner portion of the outer periphery of a circular disk containing portion along the configuration of said medium, a wall portion is formed near the central portion of said disk containing portion, and said will portion is made higher than said stepped portion.